If this is going to be your only multimeter, then having both TRMS and uA would be very good. Limiting yourself to the 17B+ or the 115 means giving up one. The question is which measurement are you more likely to need? Are you going to measuring anything AC that is not basically pure sine wave? Are you going to want to measure low millamps and microamps? Remember just because you can resolve 1mA does not mean it is actually an accurate enough reading.
The 115 is rated at 1% ±3 counts. This means a reading of 1mA could be actually off by 301%! You need the lower range to be available so you can see something more like 1.000uA instead of 0.001mA. The difference in errors on those ranges is very significant with those measurements.
Why would you need TRMS? Are you measuring audio signals? Are you trying to measure the power going to a tweeter in a speaker to be sure it isn't going to fry? Are you measuring power to devices that are temperature sensitive and you need to know the exact AC voltage and current that the device is seeing?
You really should consider another brand IMHO so you can get the functions you want. For close to the same price as the 115 you can get the BM857s. Have a look and ask yourself if having a Fluke is that important to you.
http://www.tme.eu/en/details/bm857s/portable-digital-multimeters/brymen/People have reported somewhere around $10 shipping to NA.
50000/500000 counts, 0.03% accuracy, dual display, TRMS AC+DC, PC connection option, and many others. It gives up battery life, touch hold, and lifetime warranty against the 115.
Or the AM-270 as I mentioned. $110 and has the two feature you want together, TRMS (AC only) and uA. The back light is a joke though.
The UT139C I referenced is a low priced meter with everything most hobbyists need. What many hobbyists need and don't know until they run into it is that they need two meters at the same time. This is where you can buy two UT139C and have all the capabilities you might need. It is TRMS AC only, and has all he other functions most people would need.
Remember I sell Brymen only South America and make no money recommending it to anyone else. I also make no money recommending Amprobe nor Uni-T. Uni-T has so many crap models it is hard to recommend them but I have the UT139C here I have been using and testing has proven itself to me to be a worthy meter and especially for the price. You can get it from Franky, iloveelectronics here on the forums, for $50 shipped. He will take care of you better than any other retailer I know.
Just so you know, I own a Fluke and have used many of their models over the years, Brymens, Uni-Trends, Digiteks, Mastech
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/xfacepalm.gif.pagespeed.ic.EBDwh1hCfo.png)
, Metex, one Victor that has been surprising in accuracy over 5 years, UEi, and a couple of others I am probably forgetting. My point is that I understand the confidence in Fluke, but confidence should not over ride your needs in functions. I have as much confidence in Brymen or I wouldn't have started trying to sell them in one of the most difficult markets in the world here in SA. I also make my other brand/model recommendations with the same confidence with the caveats I always include in my recommendations. I make NO money in all the recommendations I have made to you here. I just want to help.
Edited for grammar