Definitely the oven. It's not just a gross job, but incredibly tedious as well, and something I personally don't get any satisfaction from. Next time I buy an oven the number one priority is that it will be a pyrolytic self cleaner, and any other features will be of secondary importance.
The only things I iron are collared shirts (I prefer them starched) and perhaps the occasional pair of jeans if deeply creased. Other than that, I hang or fold everything straight out of the dryer while still warm and consider it to be "good enough". If it bothered me that much, I'd get an ironing lady instead.
Dishes, I will not do. I don't have room for a full size dishwasher, or even a slimline one, but was determined to come up with something and eventually managed to shoehorn in a countertop machine. Always dismissed the idea of these previously, but after living with it for a few days was surprised to find that you really can fit quite a lot into them. Everything goes in, including pots, pans, oven fittings, extractor hood filters and so on. Two years on, I still think this is one of our better buys.
Don't like dusting one bit, so I try to make it as easy as possible. That means very little in the way of ornaments and clutter lying around the place. No bookshelves, no CDs/DVDs on show and absolutely no cabinets full of knick-knacks! I find having lots of stuff depresses me; being surrounded with things everywhere I look makes me feel hemmed in, and knowing I then have to look after and clean it all feels like a massive imposition on my time. If I see flat surfaces that can be quickly dusted over without having to clear junk out of the way first, I'm much happier all round.