With a druid?

[Darkatar]

Dru/Nec for sure.

You'll save the necro tons of mana with your infinitely cheaper snare (which has no dot component..but this leaves the necro with more mana for their better dots)

The necro will heavily benefit from your Regen and later from your skin like nature/natureskin/(in velious, POTG)

The druid will benefit from the extreme amounts of spare mana the necro finds his/herself with and can get away with a twitch here and there to keep mana flowing while kiting for the pet.

With this combo you should rarely be in a situation where being OOM // having a med break becomes an issue. If you both are getting low, drop a snare and a flame lick on the nearest exp mob and kite for the necro pet (and possibly charmed animal, in the later levels) to beat the mob down (with no 50% exp theft cuz grouped)

As a Good/neutral (druid) and evil (necro) aligned characters, one of you should be able to interact vendors anywhere, excluding cabilis (unless the necro is an iksar, which I would recommend. The regen is worth the exp pen imho)

If necro is not your cup of tea, my second recommendation would be an enchanter.
The druid can snare the enc's charmed pet to keep charm breaks safer, thorns on the enc charmed pet for a very beastly pet tank, or just kite like you would with a necro, and enc C for mana regen constantly while kiting.

Mage is another good choice for a druid combo, with reasons why similar to above. You may find the lack of mana regen bonuses a bit discouraging (until velious) but a mage pet rocking weapons quickly minces up most mobs (expecially later water pets) unless you run into healers. At which point you have the 2nd and 3rd best nukes in the game to burn them down.

Now, in the endgame with any of these choices, summoning mobs/kiting (the kiteable areas get slimmer and slimmer as you level)/no slows (unless enchanter) may/will become an issue, but with proper fearing/pet control/pulling you shouldn't have any real problems taking the duo to 60.