And a MAJOR weakness of EF is that it can't display reward flight availability of SQ, NH, OS, TG, LH (I don't really care much about UA). So this renders the flight alert part of EF useless.:td:

Wish KVS put in this flight alert feature soon!!!

Only useless if you need that information - I do not.
Seems others want this to get into a p*ssing contest between tools. :rolleyes:
Use the tool you want and which does what you need.
I have used both EF and KVS tools over the years.
I now choose to use one over the other. EF suits me better for my needs at this point-in-time.
Nothing more - nothing less.

Thanks for the feedback. When i joined the EF 5 day trial, I had an expectation that I could check US/CO/UA reward availability...Apparently not. That's ok. I find the AP rewards site terrible for finding seats, especially on *A, for example, out of BUF. I do like the ANA site and use that most often but I find that it is limited to only searching for 1 stop itineraries. If you have, or are willing to fly and have two connections, then flights don't show up, you have to build them yourself.

+1^

comparison
 

I suppose this will really set the cat among the pigeons, but would anyone be willing to take a stab at a comparison, at least in general terms? What are the strengths and weaknesses of the two? What kind of travellers likely do better with one or the other, and who needs both?

Do not have time to do comparison.
If you want input from one who does 300K+ travel both International & NA
and who has tried both KVS & EF.
I would say EF hands down.
I found many GDP mistake fares on EF.
The shortfall of award travel info on EF can be had from very reliable ANA Tool free.
My 2 cents.

I use the ANA tool. It's a fantastic tool and easy to understand. :)