Some of the best outstanding mophead blues can be had with Blue Prince, Enziandom, Generale Vicomtesse de Vibraye, Hamburg, Marechal Foch, the various Merrit Supremes and, of course, Nikko Blue. For lacecaps, try Blaumeise, Blue Bird, Blue Deckle and Nightingale. There are more, of course.

That said, a highly acidic soil with lots of naturally occurring aluminum is required to achieve good blues. A soil pH of 5 or less helps so determine your soil pH and plan how to tweak it on an on-going basis every year forever. Note that this can be quite a pain and it is easier to achieve/control if you have potted plants. A soil pH testing kit that measures soil pH in numeric values, as opposed to using colors for the results, is probably preferable in cases like this. Limit use of lime on the soil. Some people add high nitrogen/potash and (somewhat) low phosphate fertilizers too, say, oh, those fertilizers with a NPK of 25/5/30 but do not fixate on must-having exactly that. Organic compost and composted manure are good choice too. A formal soil test can determine how much naturally occurring aluminum you have and aluminum phosphate can be used if the soil is wanting.

Fall colors may be difficult to achieve with macrophyllas. I find average fall colors with mopheads and lacecaps (usually yellow or "brownish") but very good colors with oakleaf hydrangeas (which unfortunately do not bloom blue).

That's a big list to choose from, thanks!

All macrophyllas are blue here. Well, I've seen a few white ones, but we just don't grow pink ones in our soil. At least not that I've ever seen. I know my grandmother never tweaked her soil pH. But I'll test mine in that specific bed.

I really like Nightingale.