Looking for the most accurate and detailed map card for a humminbird 1198c. What's your recomendations?

Lakemaster or Navionics. You'll get different opinions of which is best.

get both.

I like the lakemaster but you are SOL if lake you're fishing is not offered. I have both but will use lakemaster when lake is offered

^^^This.

Have lake master right now. Didn't know if there were any others better?

Can you use both at the same time?

I looked on-line and on the Humminbird site they do not list a Lake Master version that has Texas lakes on it. What am I missing?

put one in the right card slot then put the other in the left.

you will have to switch back and forth

Is there an advantage?

Yep lake master has a shallow water offset that kicks but. Road beds are like driving down the road. And creek channels are simple to fish.

Yes, they offer maps with Texas lakes BUT what everyone is talking about, they might not have the lakes you fish. There is a list of maps on their site. Look at it and make sure that they have the lakes that you fish listed. Also check to see if they have it in HD. They also offer just the specific lakes that you want to download to an SD card. If you only fish one or two, that might be an even better way to go. I glanced at them and they ranged from $3.99 to $9.99 per map depending on which lake.

You can choose which map card you want to use but I don't think that you can use them both at the same time. They have different features and one might be better for you on one lake but the other might be better on another lake. I have Lakemaster and I enjoy the depth feature so I can set it to the correct lake depth when I get there.

One more suggestion, the current Navionics maps can be viewed on the Navionics websites's Web App.
You can see the Nautical Charts and Sonar Charts.

The Web App is updated daily "somewhere"

Humminbirds run much better and precise with Lake Master Card. Some really cool features and they have a lot of Texas lakes. Even Squaw Creek with a lot of detail.