The pre-war BSA rifles are superb, particularly the pre 1917 or so ones and there are enough variants to keep most people amused. But do not overlook the, maybe, less appreciated models from the post WWI era: the BSA breakdown pattern and the early Diana 27 for instance. I particularly like the Diana 27 rifle and it's clones and they make superb shooters and are very easy to service. Then you have the Webleys ... the Service MKII and the MKIII. The former is really quite expensive these days, especially if you find a set with two or three barrels (.177, .22, .25) but you might be lucky in getting a single barrel rifle at a more reasonable price.
But it gets addictive and before long your house will ring with those immortal words .. 'Just one more ....'. And, of course, you will start spending more and more time scouring the auction catalogues.
But it's fun ...
Cheers, Phil