well i find that the .187 female quick connects are good, but for one wire at a time only. not good if you are daisy-chaining quick connects for ground since you have to fit two 18 gauge in there...
since i have the 18 gauge to use for the daisy-chained ground, i ended up using the .250 fully insulated for 16-14 gauge wires, twisted up two 18 gauge wires and slipped those in and crimped. then i used pliers to bend and "crunch" the LIP end some so it will snuggly fit the microswitches' connection LIP.
Gauge has nothing to do with the tab size, except whether or not the store carries a certain combination or not.
I have .187 tab, 22-18 ga. quick connectors for the N.O. wiring, and .187 tab, 16-14 qa. quick connectors for the daisy chained GND wiring. Also, some of my switches use .250, so I also have .250 in both 22-18 and 16-14 guage sizes. The 22-18 guage has red plastic covers, the 16-14 guage are blue.
If your local electronics has both sizes, and you use 18 gauge wires, I suggest getting both sizes. It really made daisy chaining a lot easier. FWIW, I got most my .187, 16-14 ga from Fry's Electronics, IIRC; radio shack didn't have this combo.