Dillema?

I just started a Channeling ritualist, and I don't know whether to have Monk as secondary, for healing or mesmer for energy stealing?

Neither one - would be my answer. Whether you are doing a straight Channeling DPS build, or an SoS spirit spammer, you don't really need anything other that Rit skills.
On the other hand, to better answer your question - I don't think you should be concerned about healing as a Channeling Rit (leave the healing to the Restos), so I'd go for the energy steal, if you must. I've never found energy to be much of a problem with a Ritualist, but maybe it's the energy loss for the foe you are interested in, more so than the energy gain for you.

Channeling rits (at least if they are using spirits) have access to a superb energy management skill: Spirit Siphon.

As Quaker said, you will probably only use rit (and pve) skills anyway, so your secondary doesn't really matter. Choose either one, you will be able to change it later anyway.

so what secondary is a good one?

Anything that can help do what you want to do. Channeling has several options, so it depends on which option you are using as to which secondary will offer the best skills. For instance, if you are running a spirit spamming build, you may want more spirits to take along from the Ranger class (Edge of Extinction, Quickening Zephyr, etc.) but it would depend on the team build and what thew purpose of the spirits you had were. Or if running a spell casting build, you may want things like Arcane Echo, Channeling, Power Drain, etc. from Mesmer, or Glyph of Lesser Energy from Elementalist. Yet some missions/areas may require things like hex removal or IMS skills. There are just too many variable, so figure out what you are doing, how you want to do it, and then find skills that may help.

monk is nice for hex removal (which rits lack).

Read Section 6 of the Ritualist basics thread in Campfire. It will give you information on secondaries. Personally, I would take Mesmer.

http://www.guildwarsguru.com/forum/b...t10245690.html