Ive got some big Rector plastic capped pads from the 90s. They have velcro straps but also the whole backing velcros round (rather than slip-on). They are fine, nice padding for the fall, put also plastic capped for sliding.
I use Bicycle Union pads most of the time. They are more like gaskits but they are plastic caps so they stop the chance of a little stem/knee contact taking you out for the night. They aint much good if you fall on your knees cos they dont have much padding, but they are small and easly go below jeans.
Ive never had a set of pads that fitted first time. I always have to make them tighter. Ive done everything from a proper job using a sewing machine, to doubling over the straps and sticking them down using Gaffa tape