You really do not really need to choose a different style of martial art for gaining martial effectiveness. What you generally need is a different way to practice Taijiquan.
The big mistake is that most people unfamiliar with Taijiquan blindly believe half-truths, lies and fairytales of those practitioners of Taijiquan who have not either due to lack of training or character learned the martial aspects of Taijiquan.
Sometimes they are not to blame for they’ve themselves fallen for the same fairytales by their teachers and now perpetuate the lie that Taijiquan is not a fighting art.
Unfortunately, since the focus on softness and meditative aspects are easy to teach and do not require any physical exertion, it has become rather popular form of the art to only focus on meditative, medicinal and choreographic aspects of the training, ignoring everything else.
In truth, Taijiquan is and can very well be just as effective as any other martial art so long as you put in the training necessary to develop martial skill. This means including practice of martial applications and free sparring and some general body strengthening and endurance building exercises in the curriculum. It also means learning to use proper amounts of softness and hardness, generating power when necessary and letting go of tension when tension is not needed.
It also means you need a teacher who can set you on your path and correct your mistakes and a partner to practice those things with and offer you a proper resistance.
It also means they you need to test your martial skill with other martial artists regularly. Preferably against representatives outside your immediate training group. You need this because they give you important feedback that your group can not. And you need to learn from your mistakes and integrate this into your Taijiquan.
It is possible and getting some basic level of martial effectiveness does not take years or decades as the popular legend around Taijiquan seems to suggest. Sure, you won’t reach a master level effectiveness in years to come, but same is true for any other martial art, so why would Taijiquan be any different.