In 2024 rules I built a way of mercy monk, but I started with one level of rogue for skill proficiency, backstory and proficiency with daggers as a monk weapon

im trying to rebuild him with 2014 rules, but I can’t figure out if it’s worth the one level of rogue now

any advice?

Well, one thing I'll point out is that the Monk class provides proficiency with daggers (and they count as a Monk weapon) in both 2014 and 2024 rules; there's no need to multiclass for that.

One level of Rogue gets you Sneak Attack, but Sneak Attack scales based on Rogue level, so if you go full-on Monk after that, its usefulness is going to fall off pretty quick. The extra skills and expertise are nice, but whether that matters or not is going to depend a lot on who else is in your party and whether they have a good spread of skills without you.

From a mechanical perspective, I would lean towards it not being worth it.

Is it worth it?  That depends entirely on what you hope to gain from the particular multiclassing?   For me, if I chose to dip, it would be a single level of Bard for the damage resistance in Rage. And that would be based on if the DM was pretty sure we'd never come close to 20th level. 

single level of Bard for the damage resistance in Rage

You mean barbarian or is it a Keith Moon class?

I am under the impression that as the 2024 version is so much better, implies it is not worth it to even do 2014, but not having the books I am not sure.

As you do get a lot of monk improvements, it is probably not worth while to dip a level as there is not a lot of level 1 advantages that are superior to that higher level in monk.

Quote from wagnarokkr >>

Well, one thing I'll point out is that the Monk class provides proficiency with daggers (and they count as a Monk weapon) in both 2014 and 2024 rules; there's no need to multiclass for that.

One level of Rogue gets you Sneak Attack, but Sneak Attack scales based on Rogue level, so if you go full-on Monk after that, its usefulness is going to fall off pretty quick. The extra skills and expertise are nice, but whether that matters or not is going to depend a lot on who else is in your party and whether they have a good spread of skills without you.

From a mechanical perspective, I would lean towards it not being worth it.

 I’m wondering if the OP meant mastery in daggers, not proficiency. That extra nick attack doing martial arts damage die is appealing. Plus more skills and expertise. And while absolutely the d6 damage falls off in value pretty quickly, it’s better than a poke in the eye.
Personally, I’d still stick with single class 24 monk, as you can get expertise through a feat, but I can see it being a little tempting. 

Quote from Character77006 >>

single level of Bard for the damage resistance in Rage

You mean barbarian or is it a Keith Moon class?

I am under the impression that as the 2024 version is so much better, implies it is not worth it to even do 2014, but not having the books I am not sure.

As you do get a lot of monk improvements, it is probably not worth while to dip a level as there is not a lot of level 1 advantages that are superior to that higher level in monk.

Honestly, I would tend to agree. Not Getting Hit In the First Place is superior to Soaking Much Damage in most cases, and the '24 Monk is very good at Not Getting Hit If I Don't Want To Be.

Also, having to have 13 STR, 13 DEX and 13 Wis for the Multiclass. Strength is mostly redundant on a Monk. Bonus actions are also load-bearing for Monks in my estimation; Burning one to activate Rage is pricy.