Ronand,
If you can afford the £13000 difference between the xls and 737 type ratings, GO for the 737 !!!!
As a relatively low-time pilot, you will get a lot of very valuable experience with Ryanair, and, in a couple of years, if you don't like it, you will probably have a lot more opportunities than you do now!
73, Ronand, 73!!
Regards,
Goose
(even though I fly the XLS myself...)