When do you fish each? If im looking for numbers of fish, which is better?

It depends on conditions. When I fish a worm on a jig head it's a light head and a small worm fished on light line in clear water and light cover. I throw T-rigs in grass and wood cover and are typically 1/4oz> with a beaver or creature or bigger curl tail worm 6">.

If its a tough bite or I need a fish in a tournament I will throw the shakey head.  Its a limit catcher.  If I am looking for a bigger bite or fishing tight to cover I will go T Rig. 

For numbers the shaky head is what you want to use. I look at the T-Rig as more of a moderate to heavy cover presentation in small areas while the shaky head is a sparse to no cover presentation used to cover a wide area. I typically use larger baits on the T-rig but over the last 3 years I've been using bigger baits with a shaky head and a technique shown to me by a friend is a 3/8oz shaky head with a 5/0 hook and a 10" worm fished along  tapering points, killer presentation.

I throw a t rig in much shallower water than I will a shakey head. I like a shakey head over pea gravel, chunk rock, points etc also.

Like most people I like a shakeyhead in sparse cover.  My favorite lake has a shallow plateau bordered by ledges. just inside the ledges are a ring of sparse rushes with a rocky bottom. thats where I fish a shakeyhead.  when I move inside the rushes the bottom is covered in weeds and lilypads thats when the T-rig comes to play.

Depends where the bass are holding.

 

Tight to bottom.

Tight to structure.

Swimming around.

How high off the bottom are they swimming around.

Will a plastic waving in the current PO them more than a plastic sitting on the bottom?

 

Applications for both depending on where the fish are holding.

In a dock fishing scenario I use the shakey head to keep the bait upright once it hits bottom so I can dead stick it or slowly drag it for that soft cold water bite.  In warm weedy water where I'm getting bit before the bait even hits bottom, then I prefer the texas rig. 

If its a tough bite or I need a fish in a tournament I will throw the shakey head.  Its a limit catcher.  If I am looking for a bigger bite or fishing tight to cover I will go T Rig. 

x2

 

I also tend to use a T-rig over a shakeyhead for grassy cover and dissecting cover. If there is gravel and clear water, it's time for a shakeyhead. 

I do most of my shaky head fishing around docks. If I lose more than three on a line of docks, then I will switch to a "finesse " t-rig with a 1/8oz weight and floating worm. Works about the same but I can come through trash MUCH better with it.

Shakyhead is more of an open water/sparse cover technique for me while the T rig gets the most work around cover or weeds. 

Shakyhead is more of an open water/sparse cover technique for me while the T rig gets the most work around cover or weeds. 

Yup....

Shakyhead is more of an open water/sparse cover technique for me while the T rig gets the most work around cover or weeds. 

 

This. Also accompanied by light line and finesse baits on the Shakey Head and heavier line and larger baits with the T-Rig.

Shakyhead is more of an open water/sparse cover technique for me while the T rig gets the most work around cover or weeds.

One more vote this advice.

I'll use a shakey head in cold front conditions, or when I'm confident about a spot. I like it in timber vs. brush or around boulders vs. gravel under those conditions. The T-rig gets the nod when I want to use a faster presentation or as a search bait.

The only time I use a shaky head around grass is if I am using a bait that I plan to swim or work faster after casting to a piece of cover I want to work slowly. I find if the bottom is grassy your shaky head will just vanish, but if I want to cast toward a bunch of branches mixed into the weeds, I may try the shaky head rigged weedless with the screw, and usually use a swim senko or Ribbon tail, shake it a bit and lift and fall to hopefully get a fish to bite that is in that area, and if not, I can swim the bait out slowly and get a bite hopefully.

 

I also consider a shaky rig to be a hard bottom lighter line 6-10lb test fluoro techinque, but I would think it would work well on heavy braid if you have hard bottom under a mat, some of the new shaky heads like the Megastrike version in light weight lands on top of the grass and will not vanish and it is a good design for hopping or dragging...The Megastrike Shaky heads are legit, I love em in the phoshpate pit ponds we have in Florida with hard bottom, I do well with them no matter what worm I put on them, or tube.