First of all, if you are travelling long-term, then an annual travel insurance policy won't cut it, as usually they only cover trips up to, say, 30 days in length. They are meant for regular travellers doing short trips, not long-term travellers. Really annoying, as you can get some astonishingly cheap annual travel insurance policies these days :(
I would suggest that a backpacker policy might be a good idea for you. I've always taken out backpacker policies and they seem to fit my needs well. They will cover possessions, medical cover and also personal liability, but the limits might be small (e.g. for possessions, the claim limit will likely be £100-£150 per item, so it won't cover an expensive camera, smartphone, laptop etc).
I have always used
World Nomads (that is an affiliate link, I get a little bit of commission if you use it!) for my long-term travels and have always been happy with the cover and claim process (I've claimed twice successfully), but I am starting to think they are on the expensive side; they have a brand to maintain, I guess. You'll probably find other backpacker policies with similar cover for cheaper. Although one thing I like about World Nomads is that you can take out/extend a policy when you're already on the road; lots of other insurers require you to be in your home country when you take out a policy and don't allow you to extend on the road, bizarrely.
Hope that helps!