1970s and '80s Canons are not modern cameras, you have to appreciate their period charms to get on with them. I was always a Nikon person but since the market in film cameras (mostly) collapsed, I've tried various brands, including Canon FD. I have the majority models, but return to particular favourites. The main advantage of Canon FD is the cost of lenses compared to other marques, especially Nikon, although mirrorless and video users have seen prices rise in the last few years.
The T90 is a very good user SLR if you need solid metering, and are prepared to put up with the weight, film advance noise and menus. The latter are child's play compared to newer cameras, but obviously not as simple as an FTb (which is an excellent camera if you can get round the defunct batteries). The A-Series have the advantage (to me) of manual film advance and readily available batteries. My favourite is the AV-1, an aperture priority only SLR that's a great point and shoot camera. It's taken out more often than my other A's and T's and the metering is reliable. I haven't bought an F-1 because heavy cameras don't appeal any more, and they are expensive and/or well-worn compared to non-professional cameras, but they have a good, though not flawless reputation.
The FD 50mm f1.8, new or breech mount, is an excellent lens, better in some ways than the lauded 1.4 which suffers from focus shift around f2.8 - f4. Put a period lens on a digital camera and it shows its age, with the usual aberrations, or character depending on your point of view. People tell me Zeiss, Leitz, Angenieux, etc, stand up to modern glass but my experience of older manual lenses, including Nikon, is they perform best on film cameras.
My T90 was ridiculously cheap because of a sticky shutter, but the CLA cost less than £40 and it has proved a great buy once you learn to live with its quirks.