Contemporary written usage of "whom" in objective case [duplicate]

Possible Duplicate:
What's the rule for using “who” or “whom”?

I was writing a LinkedIn recommendation one day, and ended up pondering for a while which of these forms to use:

… is a great developer whom I always found easy to work with.

… is a great developer who I always found easy to work with.

Both are basically correct in contemporary English, right? But is one or the other preferable, and if so, why?

_{(In this case I went with the latter, as it seemed more common (Google) and I wanted to avoid sounding unnecessarily “archaic”, although I’m not sure whether that would have been the case. Also note that I try to write in a “friendly professional” style instead of overly formal one. :-)}

Solution 1:

As you can read at the other question, whom is correct, but substituting who is acceptable to many.

If you want to be more formal and satisfy the nitpickers you would probably also want to avoid the preposition at the end of the sentence. Consider rewriting the whole thing, for example:

X is a great developer. I always found it easy to work with him.

or

X is a great developer who is always easy to work with.