Fly the 152, there is a reason why they have been one of the most enduring trainers of all time. They are easy to fly but hard to master. They give a good view of the ground which when starting out you will find helps with your nav. On a hot day they are a lot cooler as the wing protects you. And above all they are cheap to fly.
I bought one a year after my PPL and just sold it after putting 1200hrs on the clock and enjoyed every minute. It was a teafull parting but at least I swapped it for another Cessna!
As far as "conversion" is concerned to other types if you can fly a Cessna you can fly a warrior. I have never taken more than a couple of circuits to get the feel of another SEP. Read the POH to understand the numbers and of you go, its not rocket science. People who take a couple of hours to go from 1 152 to a warrior or vice versa were probably marginal in the first place or they are being turned over by the school. My Multi Engine was only the required 5hrs!