What's with all the nicotine craze lately? If your primary objective is nicotine, I'd propose buying some patches and gum. Seriously. If you insist though, I'd recommend you first try GLP Jack Knife Plug and Mac Baren HH Bold Kentucky. You can ramp up from there with some Gawith ropes/twists.
I'm still new to this game and one of the more surprising things I found with pipe communities is that desiring strong nicotine content is a real faux pas with many. As someone who initially came to pipe smoking explicitly
for the nicotine (not wanting to wait anywhere between 4 and 20 days for snus and braving the cravings) and stayed for everything else, I can answer.
I'll say first that I no longer buy snus, the slow release of nicotine through pipe smoking let me fade that habit out without going cold turkey. I'll also say that the everything else is the "primary objective" of pipe smoking and I quickly learned that when I started—but—I still
love the nicotine hit of a first pipe smoke of the day and surely pipe smoking would never have existed so near ubiquitously in the past if it weren't for the enjoyment of nicotine? It's a subtle thing, not like snus that slaps you round the face, but it's part of the soothing smoking experience. Even if you only smoke blends with barely any nicotine, your tolerance will be such that barely any nicotine is all it takes to have an effect.
This doesn't reduce pipe smoking to chuffing a cigarette in 30 seconds purely to feed the addiction, it's still the haughty and sophisticated hobby we know and love, but mixed in with the flavours and sensory pleasure is the enjoyment of nicotine on the brain.
So "seriously", nicotine gum is expensive and intentionally disgusting in addition to being woefully weak. Patches stave of withdrawal, they take slow release to another level. Pipe smoking is obviously far more enjoyable than either of these and lets you enjoy the effects of nicotine, not just avoid the craving. Those are solutions for people who want to kick their addiction, not enjoy the chemical reaction the same way a coffee drinker does - without shame.
The aversions among pipe smokers are quite curious.