The most popular in Liverpool? That's a rather odd question to ask.
What do you want to know about -popularity- of a morph for? Are you asking for the most commonly owned morph, or are you asking about the most desired morph? The answers would be wildly different - and the answer to 'most desired' really does depend on the person asking.
And it doesn't matter a hill of beans what the most popular or desired morph is if you don't actually LIKE that morph
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I know that a good Reverse Okeetee is relatively 'desirable' - but I don't want one, personally.
If you don't want to spend much money, stick with a wild-type (AKA "Carolina" or "Classic" or "Normal" here in the UK) or one of the common morphs like an anerythristic ("Black Corn" - great if you like black, grey and brown), an amelanistic ("albino" or "red albino" - shades of red, yellow and orange with red eyes) or a snow ("albino" - white, pink, yellow and sometimes lime-green, with red eyes). You'll see plenty of these kicking around shops in the area, and plenty of breeders who've got 'em up for cheaper than most shops.
If you've got your heart set on something more unusual and expensive like a lavender or a butter or (insert current flavour of the month here), don't give up on getting that just because it's not the 'most popular' snake out there. You might well have to find a breeder for them, however...