I have virtually the same mini dilemna.
I sold a GS2 and need to replace it for my 2nd payg sim. I am using a candy bar Samsung in the meantime and it's great for calls and texts, nicely made, massive battery life and tiny. I may not buy anything.
I was thinking Moto G 8gb, 16gb or 8gb LTE with sd slot. Also like the Sony Xperia SP, but realised I can get a very good used Nexus 4 for a little more. Surprisingly a grade A condition used GS3 is way above my UK budget, the GS4 about 50-60 more again.
I downloaded the Moto G manual and tried in store. I don't know, good spec and all that but...
I could not get a Note 2 for less than 300+. If you can get a very good Note 2 for that money it's the best phone, though will run out of updates sooner. You say you already have a big phone, and I have a Note 3. For me there's also a HTC Desire 610 and Sony M2 and L. I can get a blue Moto G flip cover case for only £5, so maybe -
Not much help to you really. Be good to know what you eventually choose.