Here's a few brands and what they are:
Kirkland minoxidil- cheap, generic, lower quality vs other's but it's still effective if you're on a budget and a good responder. It's only active ingredient is minoxidil. More likely to make hair a tad greasy.
Rogaine- High quality minoxidil, no other active ingredients. Uses quality chemicals. Not cheap, not expensive.
Lipogaine- 5% minoxidil, retinol (to help increase absorption of minoxidil) and a blend of other things to possibly help combat hairloss. It says it has an anti-dht blend in it, who knows how effective it really is.
It's not cheap, about $25 for a month supply. I use it and I have maintained and had some regrowth as well.
It all comes down to if minoxidil is effective for you. Pairing it with an anti-androgen (mainly finasteride) will increase regrowth substantially.