That E30 is in really good condition. I'd hate to turn it into a DD. Oh, but you live in Cali so you don't have snow, salt and other shit on the roads.
Honestly, either car is a great choice. The E30 will be a little smaller and better on gas. The E34 will be a little more roomier and have more power. I think it really depends on which car you like better.
2004 BMW M3 6MT - B&B TriFlow section 3|AP V2 headers|AST 4200|UUC EVO3 SSK with DSSR|ZHP knob|Orion V4|Matte Black kidney/side grills|19" VMR CSL reps|245/275 Continental ExtremeContact DW|Track stuff: 9" square style 67|275/35/18 Nitto NT01|Schroth Quick Fits|PFC 08 & 01 Pads
2014 VW GLI 6MT - APR stage 1 tune|CTS Turbo intake & 3" downpipe|ST coilovers