If relying on shows only to base your judgement I would be very careful, a couple of rushed games in a noisy environment does not provide adequate evaluation of a particular title, you could play a couple of games on a
BOP and think, wow I want one but truth be told you would get bored pretty quick if it was your only pin, on the flip side you could play 2 games on a
BSD and think it's a crap drain monster, don't want it, whereas in fact the
BSD is awesome but takes some bonding time, I personally would go with a theme that grabs your attention and watch as many youtube vids as possible, playing and watching pinball is similar to having and watching sex (it is at best a guide

) but if it does not float your boat watching someone else play it, music, theme, the lights etc etc then it probably won't in the flesh and vice versa.
Personally I have just purchased what I fancied/what was available at the time and kept what felt right for me, some of the keepers were machines I thought would be out the door in a week and some I thought would be keepers were out the door in a week (RFM springs to mind) basically get some guidance and get stuck in, buy/play your 1st machine to death, if you love it, keep it and buy another one, if it's not doing it for ya, sell it for the same money and try a different one, I should imagine the most you could loose on a £1000 pin would be a £100 unless you buy a lemon and there are plenty of us on here at your disposal too make sure you don't end up buying a fruit unless it's a peach.