Thanks to its Ability Transformative Start, Ditto is the ultimate consistency booster
Grisly Salvage is the most potent of those on offer but I would start with Tracker's Instincts as you can use it from the bin
Like most Magic: The Gathering cards, the value of Regeneration depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Ice Age)
While other cards might be a bit more fancy and powerful, Mickey Mouse, True Friend lives up to its name with a very dependable, solid card thats good at a bit of everything, for a very fair price
On the off chance I do think of something I need that isnt a land panorama, I exchange a ton of e-mails with the artist
If youre in search of a rarer or older booster box (think 4-5 figures of value), you may also find that sellers have unreasonable prices attached to their listing if there arent many for sale on the market