The plane You will get a job on, I would say.
I was in Your situation several years ago and briefly meditated on doing a TR on my own like some of the guys in my flight school did - it would have been either 737 or 320 as well. But on hindsight I sure am glad I did not do this, as my first type was neither of those two but the Fokker 70. Any money spent on other TRs would consequently have been burnt.
There are several colleagues I know that went the same way - they bought a TR on whatever jet type but are now flying the DH8. Happily, I might add.