I have one account with around 25k and one account with 150k @ 3 years. The 25k account was doing well at the start but the 150k is performing
MUCH better in the last 3 months, if I could go back in time I would of created one 175k witness account.
The 150k account on some days gets 3 witness rewards.
The witness rewards are also going from 20 to 30 per block when Guldens blockchain 2.0 (Phase 4) is released.
Bigger is better when it comes to witnesses.