What's the best weight lifting routine for strength?
If you are still getting stronger, you can keep doing what you are already doing with success, until your progress stalls. I cannot count the times I improved and then changed my routine with no good reason.
From my experience (4 years of serious lifting), a good strength program revolves around two or three main lifts. Weightlifters do two lifts and powerlifters train three lifts. To get really strong, you need to teach your muscles to work effectively together, and this means lots of practice with few big, compound lifts.
It also means low rep training, but not necessarily super-heavy all the time. I'll give my own example. Today I trained my clean & press (strict). The session went like this:
95 lbs 2 sets x 5 reps
135 2 x 3
155 3 x 2 - still a very easy weight for me, but I avoid needlessly tiring myself
165 x 1, 175 x 1, 185 x 1, 195 x 1 - all easy singles done with sharp technique
205 x 1 - still easy; I decide to do one last lift with 10 lbs more
215 x 1 - slower lift, but still some power to spare (my limit is at 220–230)
Most weightlifters around the planet train along similar lines; they start with very easy weights, they don't do very long sets, even with light loads, and they focus on good technique while they ramp up their sets. This kind of training works very well for a lot of trainees, me included! I'm having a great time and I always look forward to my lifting sessions.
I used to do more different exercises, but at one point, I was overloaded with office work, so I could only train in short sessions about 3 times per week. I devoted all my training time to strict press and deadlift. I was surprised to notice that I got bigger and stronger by doing less than previously. When you want strength, quality training always beats quantity!