Oven features required/desirable for baking bread at home

This is borderline opinion based but I'll take a shot. I have used fan and non fan ovens to bake bread, and you can get excellent results either way. When I used a fan only oven I would typically make an air diverter out of tin foil to keep the fan from blowing directly on the bread, which worked really well. I also used a large ceramic coated cast iron pot as a bread cloche, and you can buy purpose made cloches for a lot less than a new oven.

That being said I have an oven with a non-fan mode now and I use that almost exclusively for bread baking as it is easier and more convenient than having to mess around with diverting the air. My primary oven has about 16 modes, half of them I don't even know what they do! I use fan, non-fan (top and bottom) and top grill almost exclusively. My secondary oven is a Neff with a bread mode and I can't tell the difference between that and regular non-fan mode. If the AEG steam oven you mention is what I'm thinking of the 'steam mode' is just a pocket to pour water into and the steam comes out of the bottom of the door, probably not something worth shelling out lots of extra money for when you can put a pan of water at the bottom instead.

You may want to have a look on local sell and swap sites, ebay and the like for used appliances, people will sell some really good stuff when they remodel a kitchen, or want something with a touchscreen.

The most important thing is that your oven can maintain a humid environment. Features such as vents, designed to reduce the odour of cooking food when you open the oven door, are therefore undesirable. Some people say that this makes fan ovens unsuitable, but at least in the UK, most new ovens are fan ovens (and often the fan cannot be disabled) and people still seem to get good results. In any case you can use a Dutch oven within your cooker to trap steam, and use low-tech methods such as a tray of boiling water.

A fan oven will maintain a more even temperature: this is important in all types of bakings, particularly for cakes where a temperature gradient can cause a lop-sided cake or noticeably uneven cooking. Accurate temperature control is also important. Oven thermostats are notoriously unreliable, perhaps because they're taking the temperature too near (or far) from the heating elements. One can work around this using a separate temperature probe situated exactly where you're going to do the baking.

Probably also not a complete answer (can there ever be for such questions?), but the main criteria for me with a focus on bread would be (in no particular order):

• Maximum temperature.
  For bread, 250°C is usually good, but speaking from experience, the step from bread to pizza is small and for those, the hotter the better.
• Sturdy rails and racks.
  I bake my bread either on a stone (2.5 cm thick, rectangular, almost as large as a baking sheet, not the flimsy round ones sometimes sold as pizza stone) or in a rather large Dutch oven. Especially the stone is heavy and I still pull out the rack halfway for some breads, because it’s easier to maneuver them. That’s a serious bit of load.
• A non-fan top and bottom heat option.
  Yes, people make good bread in fan ovens, but I have also had issues with hot air blowing onto one side (remember that turning a half-baked bread is not a good idea, as opposed to some cakes), and the fan can also prematurely “blow away” the very important steam. If you can set top and bottom heat separately, it’s nice, but not that important.
• A non-crucial but actually neat feature for bakers can be a timer that starts or stops your oven at a given time. My stone needs quite some time to heat through and a timer means that I can set it to pre-heat well before I get up, then I can just take my overnight breakfast buns straight from the fridge to the oven when I get up and we have them for breakfast with maximum convenience. But that’s just a very personal preference, not a determining feature in my opinion. I have also used it for other timed applications and it was especially handy when the kids were smaller and life a lot more unpredictable in general.

Apart from the specific use case, there’s one feature that I miss a lot at the oven I am using at the moment:

• A self-cleaning function. Of course running the pyrolysis cycle uses a lot of energy, but I hate scrubbing the oven, especially the little nooks and vent openings and roasting a chicken or something that does splatter leaves a mess, no matter how careful you are. And instead of harsh chemicals, you just need a humid cloth and perhaps some all-purpose cleaner to wipe out the ash.

A few thoughts about the various extras:

Unless you already know what you are going to use the specific features for, I wouldn’t pay extra for them, as there’s a good chance that you won’t be using them. If the oven you selected for its basic features anyway comes with some of them, fine. If your budget is large enough and you just want them for a reason (even “just because”), that’s of course another case.
And remember that the more features you have, the more can fail - a separate meat thermometer can be exchanged cheaply (or you can use multiple ones or one that connects to an app, or...), a built-in one would need either a costly repair or you would switch to a separate one in that case. Just for example.
I struggle to see how “special programs” for bread would cover the many cases of bread - your Scandinavian rye needs a totally different baking temperature gradient and time as, for example, a fougasse. But I admit I haven’t explicitly researched the feature.

I still consider myself a novice at bread baking. One point that I keep coming across is that home ovens are designed to vent steam but we want a moist environment in order to prevent the crust from setting too early before the bread has a chance to expand (and probably a few other reasons). A common and effective way is to bake the bread inside another container that can trap steam for the first half of the bake. A Dutch oven is a great option. An upside down metal bowl on a pizza stone or metal sheet will also do the trick. I have no idea how effective or expensive home oven steam options are. It is worth researching.