I used Online Bible for DOS exclusively from ca. 1993-2003. I loved it. But I had very few extra resources with it - and they were all "book" style (no commentary/dictionary modules like we understand today). Then someone put me on to eSword. Whoa.
I then exclusively used eSword for about 5 years. During that time I examined Logos/Libronix with a sample pack purchased at Sam's. It was excellent; but it's costs were prohibitive. I opted to make the "mental investment" to eSword, and never regretted it (not going to Logos).
In the Fall of 2011, I started serious experimentation with TW. By January of 2012, I had abandoned eSword. I now only use it like an "app" when creating modules for distribution. Although I no longer use eSword, I still build modules for it because conversion is so easy. I get to be a "double blessing" in module distribution.
Here's my take on these 4 software programs:
OLB - nice folks; but their module integration is not very good, and their module library is not very big. Cumbersome. There's really no reason to use it; eSword is a better program.
Logos/Libronix - excellent software; but you'll pay through the nose for it. This really is only for "professional" study. Written/supported for those involved in academia who are either 1) wrapped up in snob appeal (which is rampant in academia, even amongst Christian colleges/universities); or 2) need access to the latest publications for academic writing/study. For those willing to pay full publication price for every module they download and need "Cadillac" software, this is it. For those wanting professional Bible study software with classic (and free...) public domain materials, TW is almost as good. For the price difference, in my opinion, TW is just far better.
eSword - excellent software for those with limited computer skills (and unfortunately, most of us don't know who we are!) or those who are studying the English text of the Bible. For Bible reading, eSword is great (nothing really better). For personal devotions, eSword is excellent, and much better than logos or theWord. You read that right: for personal devotions, eSword is the best software available.
TheWord - my personal software of choice. Let's be clear: as much as Costas wants us to think that it is simple to use, unfortunately it is not. The reason for that is the level of customization. It can do so much that it is hard to grasp. The first three months I used TW, I tried to use it like eSword (old habits die a slow and painful death). As I learned the software, and especially the options that are attached to the Bible view (there are probably close to 100 different ways to configure the Bible window), I quickly fell in love with it. But - you've got to be very comfortable with your computer to maximize the use of theWord. But for those who are - wow! You're going to love it!
So....
Need to study the Bible professionally for academia? Bite the bullet and purchase everything through Logos. Ugh.
Need to study the Bible professionally for ministry? Learn how to use theWord, and you'll go deeper into the Word faster than you ever thought possible.
Need to study the Bible devotionally? Stick with eSword. It's devotional tools are excellent.
Now, that brings up an important area of overlap: which program do you use if you are a small group leader teaching adults? eSword is good, but theWord is better. If you're a layman or bi-vocational pastor, it probably comes down to personal computer skills (and not software capability). If you're good with a computer, then try TW. If you like for everything to work with a minimum number of mouse clicks, stick with eSword. (When friends want help with Bible software, I just about always recommend eSword. When colleagues talk about Bible software, I always talk about theWord.)
I hope this helps. It's been fun to write (and may end up as a blog post at my module website).