Virgin Mobile vs T-Mobile

I have decided to switch from T-Mobile prepaid phone service to Virgin Mobile. I use about 300 minutes per month on personal calls. I have a work phone that gets free pcs to pcs. I try not to use it for personal calls because I don't like to have personal numbers on the bill, which my boss sees and because we have a combined minute pool.

T-Mobile To Go Prepaid Rates
$10 card @ 50 minutes = 20 cents/minute
$25 card @ 150 minutes = 17 cents/minute
$50 card @ 460 minutes = 11 cents/minute
$100 card @ 1000 minutes = 10 cents/minute
At 300 minutes, I am spending about $51/month using $25 refills.
At 300 minutes, I would spend about $33/month using the $50 refills.

Virgin Mobile Rates
Plan 1: 25 cents/minute for first 10 minutes each day. 10 cents/minute after that.
Plan 2: 35 cents/day and 10 cents/minute.
Plan 3: $29.99 for 150 anytime/150 nights and weekends (nw). Add $10 for 100 more anytime/350 nw. Add $10 for 100 more anytime/500 nw.
At 300 minutes, I would spend about $30/month + $10 in the daily 35 cent fee for a total of $40/month.

When I reload my T-Mobile, I usually get the $25 refill or the $10 refill. Cashflow wise, it is probably better to get the $50 refill as your rate goes down significantly from 17 cents to 11 cents. The $100 refill doesn't decrease your cost enough to justify tying up that much cash. As you can see, I would save more money buying the $50 T-Mobile refills, but I rarely have $50 at once. With Virgin, my refills have gone down from $25 to $20. On top of that, I immediately get the 10 cent rate versus T-Mobile's $100 refill requirement to get that rate.