I have noticed that as I wander deeper in kava world, it is not so subtle at all. Although subtle is the word I once used to describe the kava experience, not anymore, as after four shells I am stumbling around my house and contemplating the next move of my life. The more I drink, the stronger the sessions become. I'm in love with this root.
I am krunk right now so excuse me for rambling
For a noobie, I'd suggest the Fiji waka in terms of effects. It's nice and gentle, but pronounces itself in your muscles in a nice way, very enjoyable. As for mental effects, the Fiji waka sort of gives off a nice pleasant ~feel good~ aura. This is the kava I'm currently drinking. Not as nauseous as the website says, it's actually quite easy to stomach, and the taste is relatively mild. Bula!
If you have had at least a little experience with kava and are wanting something with a little more -kick- that you can still sleep on, then the Isa/Tudei is a good pick, Douglas did a review on this one, check it out! I find this kava can sneak up on the unsuspecting user. It's really strong in the body area, and really enjoys sedating your thought process. It can be very pleasant but the higher presence of DHM means it can be much more nauseating. It's a price to pay though, as the pain relieving effects of this kava can be pure bliss.
Van3 is currently in stock, this might be your best bet. The higher kavain presence means less nausea and more euphoria. However in my experience the effects don't last quite as long as with a kava higher in DHM or DHK, but if you find those kavas get you more nauseous, then yeah, the Van3, or any other kava with a dominating amount of kavain, would be a good choice.
I don't have much experience with the Tongan, so I'll leave that up to the other more experienced members.

Good luck! Hope you are happy with whatever kava you pick! (I'm sure you will be)
Oh and P.S. - Don't stress yourself over finding the perfect kava so quickly, we all have to search around to see which one fits us, as there are tons of varieties, in which all differ in one way or another. Another real good beginner kava is the Hiwa from Hawaiian Kava Center, it's mellow in bodily effects but man, the cerebral buzz is profound and I find this to be a great base for mixing different kavas.